The Battle of Varna took place on November 10, 1444 near Varna in eastern Bulgaria. In this battle the Ottoman Empire under Sultan Murad II defeated the Polish and Hungarian armies under Wladyslaw III of Poland and Janos Hunyadi.
Prelude
After a failed expedition in 1441/1442 against Belgrade, the Ottoman sultan Murad II signed a ten-year truce with Hungary. After he had made peace with the Karaman Emirate in Anatolia in August 1444, he resigned the throne to his twelve year-old son Mehmed II.
Despite the peace treaty, Hungary co-operated with Venice and the pope, Eugene IV, to organize a new crusader army. On this news Murad was recalled to the throne by his son. Although Murad initially refused this summoning persistently on the grounds that he was not the sultan anymore, he was outwitted by his son who on the news of his refusal wrote to him: "If you are the sultan, lead your armies; but if I am the sultan, I hereby order you to come and lead my armies." Murad then had no choice but to reclaim the throne.
Forces
A mixed Christian army consisting mainly of Hungarian and of Polish forces, but with detachments of Czechs, papal knights, Bosnians, Croatians, Serbs, Bulgarians, Romanians and Ruthenians, met with a numerically superior force of Ottoman Turks. The Hungarians were ill-equipped, and were promised support from Wallachia, Albania and Constantinople did not arrive. The Hungarian army was smaller and very imbalanced. It contained almost no infantry, except one hundred to three hundred Czech mercenary handgunners. There were also one hundred war wagons probably with crews, though none are mentioned. The rest of the army was heavy cavalry, mostly Royal and foreign mercenaries, with some Episcopal and Noble banners as well. They had promises from Venetians that their fleet would not allow the Turkish army to cross the Bosphorus. There they would meet up with elements of the Papal fleet and move down the coast to Constantinople, pushing the Ottomans out of the Balkans as they went.
Aftermath
The 30,000 Crusaders were overwhelmed by 120,000 Turks. Over half of the soldiers from the united army perished. The king Wladyslaw III was also killed in the battle (he fell in a trap and was beheaded) while launching an attack without waiting for Janos Hunyadi and his forces to join him. The death of Wladyslaw III in the battle left Hungary in the hands of the four-year-old Ladislaus Posthumous of Bohemia and Hungary. In an expression of gratitude, the Bulgarian people affectionately gave Wladyslaw III the name 'Varnenchik' (Warneczyk in Polish), after the city of Varna, where he fought and died.
Follow up
The defeat ended any serious attempts to prevent the conquest of eastern Europe by Turks for several decades. It also set the stage for the fall of Constantinople in 1453.
I stand corrected. I was only looking at 1450-53.